Equivalent two-port measurement equations for reciprocal n-port network are de-rived.As an example,applications of these equations,measurement details and data-processingmethods are discussed for any three-port networ...Equivalent two-port measurement equations for reciprocal n-port network are de-rived.As an example,applications of these equations,measurement details and data-processingmethods are discussed for any three-port network.To realize rapid and automatic measure-ments of S-parameters of any reciprocal multiport network,a set of measurement system whichis composed of auto-slotted line and program controlled movable shorts is presented in this paper.Experimental data are given for an H-plane Tee three-port network.展开更多
Multiport diffusers are the effective engineering devices installed at the marine outfall systems for the steady discharge of effluent streams from the modern coastal plants, such as municipal sewage treatment, power ...Multiport diffusers are the effective engineering devices installed at the marine outfall systems for the steady discharge of effluent streams from the modern coastal plants, such as municipal sewage treatment, power generation and seawater desalination. A far field mathematical model using a two-dimensional advection-diffusion equation is presented for continuous discharges of effluent streams from multiple outfalls on a uniformly sloping beach with a current parallel to the shoreline. The analytical solutions are illustrated graphically to replicate and capture the merging process of effluent plumes in shallow coastal waters, and then asymptotic approximation will be made to the maximum shoreline’s concentration to formulate effluent discharge plume dilution from a multiport diffuser.展开更多
Laboratory experiments were conducted to investigate the mixture of wastewater discharged from a submerged multiport diffuser in the Nantong sea-area. The process was then simulated with a three-dimensional numerical ...Laboratory experiments were conducted to investigate the mixture of wastewater discharged from a submerged multiport diffuser in the Nantong sea-area. The process was then simulated with a three-dimensional numerical model. The plane or line patch was used to impose the discharge momentum flux in the near field. A comparison of model simulation with laboratory experiments shows that the proposed model can be used to simulate the shapes of pollution plumes, the distributions of excess concentration, and the velocity induced by a coflowing diffuser in proximity to a shoreline boundary. From the numerical simulation and laboratory experiments, it is recommended that the multiport diffuser be placed in a hydrodynamically active sea-area.展开更多
To evaluate the impact of the randomness and correlation of photovoltaic(PV)and load on AC/DC systems with a multiport current flow controller(M-CFC),this paper proposes a probabilistic optimal power flow calculation ...To evaluate the impact of the randomness and correlation of photovoltaic(PV)and load on AC/DC systems with a multiport current flow controller(M-CFC),this paper proposes a probabilistic optimal power flow calculation for AC/DC systems,based on a nonparametric kernel density estimation.First,according to the M-CFC model,the DC power flow calculation method with M-CFC was inferred,and its influence on line loss was analyzed.Second,a nonparametric kernel density estimation with an adaptive bandwidth is used to accurately describe the probability distribution of the PV and load,and correlation samples of the PV and load are obtained by the mixed copula function.Then an optimization model that considers system loss and static security is established,and a fast nondominated sorting genetic algorithm based on the elite strategy(NSGA-II)is used to calculate the multi-objective probability optimal power flow of the AC/DC system.Finally,a case study is performed on a modified IEEE39 bus system using measured PV and load data.We verified that the nonparametric kernel density estimation with an adaptive bandwidth can better adapt to random component uncertainty,and M-CFC can improve the static security of the system.展开更多
背景与目的肺癌术后3个月的生活质量在不同手术入路之间的关系尚不明确,本研究旨在对比单孔与多孔胸腔镜肺叶切除术后3个月患者的生活质量。方法收集2021年4月至2021年10月在四川省肿瘤医院胸外科行肺部手术患者的资料,采用欧洲癌症研...背景与目的肺癌术后3个月的生活质量在不同手术入路之间的关系尚不明确,本研究旨在对比单孔与多孔胸腔镜肺叶切除术后3个月患者的生活质量。方法收集2021年4月至2021年10月在四川省肿瘤医院胸外科行肺部手术患者的资料,采用欧洲癌症研究与治疗组织生活质量核心量表C30 (European Organization for Research and Treatment of Cancer quality of life core 30,EORTC QLQ-C30)和肺癌生活质量量表29 (Quality of Life QuestionnaireLung Cancer 29,QLQ-LC29)收集患者的生活质量资料。将基线资料中潜在混杂因素纳入多因素回归模型中校正,比较两组患者术后3个月的生活质量与传统临床结局。结果共纳入130例肺癌患者,男性57例(43.8%),女性73例(56.2%),平均年龄(57.1±9.5)岁。两组患者基线资料中,放置引流管数量具有统计学差异(P<0.001)。经回归模型校正后,在术后3个月时,两组患者全部症状及功能状态评分无明显差异(P均>0.05)。多孔组的手术时间(120.0 min vs 85.0 min,P=0.001)、术后住院时间(6.0 d vs 4.0 d,P=0.020)比单孔组更长,早期>2级并发症发生率(39.0%vs 10.1%,P=0.011)比单孔组更高。结论单孔与多孔胸腔镜肺叶切除术患者在术后3个月时具有相似的生活质量。单孔组在手术时间、术后住院时间及术后早期并发症等传统临床结局指标上可能具有一定的优势。展开更多
该文提出了一种多端口直流–直流自耦变压器的拓扑,该多端口直流自耦变压器用于互联多个直流电压等级不同的直流系统。提出了多端口直流自耦变压器的潮流直接分析法以及潮流分解分析法,推导了多端口直流自耦变压器中各换流器额定电压与...该文提出了一种多端口直流–直流自耦变压器的拓扑,该多端口直流自耦变压器用于互联多个直流电压等级不同的直流系统。提出了多端口直流自耦变压器的潮流直接分析法以及潮流分解分析法,推导了多端口直流自耦变压器中各换流器额定电压与额定功率设计方法,设计了多端口直流自耦变压器的控制策略。以一个三端口直流自耦变压器为测试算例,在PSCAD/EMTDC下仿真验证了多端口直流自耦变压器的技术可行性。以互联±250、±320 k V和±400 k V直流系统为例,假设±250 k V和±320 k V系统的额定输入/输出功率分别为500 MW和1 000 MW,采用常规的多端口直流–直流变换器技术所需要的换流器总容量为3 000 MW,而采用多端口直流自耦变压器技术所需要总的换流器仅为775 MW,所使用的换流器总容量仅为现有技术的26%,显著节省了成本,降低了运行损耗。展开更多
研究了一种基于多端口DC/DC变换器(multi-port DC/DC converters,MPC)的混合储能系统(hybrid energy storage system,HESS),并将其应用于直流微电网。针对脉动负荷功率突变对直流母线电压及蓄电池组正常运行造成剧烈冲击的问题,提出了...研究了一种基于多端口DC/DC变换器(multi-port DC/DC converters,MPC)的混合储能系统(hybrid energy storage system,HESS),并将其应用于直流微电网。针对脉动负荷功率突变对直流母线电压及蓄电池组正常运行造成剧烈冲击的问题,提出了一种基于移动平均滤波算法的自适应能量控制策略(adaptive energy control strategy,AECS)。首先,通过移动平均滤波算法将脉动负荷功率进行滤波,由蓄电池组承担平缓的功率变化,而由超级电容器补偿瞬时的功率突变,从而优化蓄电池充放电过程,延长其使用寿命;其次,引入超级电容端电压自适应控制,将超级电容端电压稳定在参考值附近;并对蓄电池组端口采用能量流均衡控制,使各蓄电池组荷电状态(state of charge,SOC)趋于一致。通过仿真和实验,验证了所提出的能量控制策略的有效性。展开更多
文摘Equivalent two-port measurement equations for reciprocal n-port network are de-rived.As an example,applications of these equations,measurement details and data-processingmethods are discussed for any three-port network.To realize rapid and automatic measure-ments of S-parameters of any reciprocal multiport network,a set of measurement system whichis composed of auto-slotted line and program controlled movable shorts is presented in this paper.Experimental data are given for an H-plane Tee three-port network.
文摘Multiport diffusers are the effective engineering devices installed at the marine outfall systems for the steady discharge of effluent streams from the modern coastal plants, such as municipal sewage treatment, power generation and seawater desalination. A far field mathematical model using a two-dimensional advection-diffusion equation is presented for continuous discharges of effluent streams from multiple outfalls on a uniformly sloping beach with a current parallel to the shoreline. The analytical solutions are illustrated graphically to replicate and capture the merging process of effluent plumes in shallow coastal waters, and then asymptotic approximation will be made to the maximum shoreline’s concentration to formulate effluent discharge plume dilution from a multiport diffuser.
文摘Laboratory experiments were conducted to investigate the mixture of wastewater discharged from a submerged multiport diffuser in the Nantong sea-area. The process was then simulated with a three-dimensional numerical model. The plane or line patch was used to impose the discharge momentum flux in the near field. A comparison of model simulation with laboratory experiments shows that the proposed model can be used to simulate the shapes of pollution plumes, the distributions of excess concentration, and the velocity induced by a coflowing diffuser in proximity to a shoreline boundary. From the numerical simulation and laboratory experiments, it is recommended that the multiport diffuser be placed in a hydrodynamically active sea-area.
基金Supported by National Natural Science Foundation of China under Grant Nos. 10325523 and 10775048the National Fundamental Research Program of China under Grant No. 2007CB925204the Key Project of Education Department of Hunan Province under Grant No. 08w012
基金supported by the National Natural Science Foundation of China(Grant No.51677023).
文摘To evaluate the impact of the randomness and correlation of photovoltaic(PV)and load on AC/DC systems with a multiport current flow controller(M-CFC),this paper proposes a probabilistic optimal power flow calculation for AC/DC systems,based on a nonparametric kernel density estimation.First,according to the M-CFC model,the DC power flow calculation method with M-CFC was inferred,and its influence on line loss was analyzed.Second,a nonparametric kernel density estimation with an adaptive bandwidth is used to accurately describe the probability distribution of the PV and load,and correlation samples of the PV and load are obtained by the mixed copula function.Then an optimization model that considers system loss and static security is established,and a fast nondominated sorting genetic algorithm based on the elite strategy(NSGA-II)is used to calculate the multi-objective probability optimal power flow of the AC/DC system.Finally,a case study is performed on a modified IEEE39 bus system using measured PV and load data.We verified that the nonparametric kernel density estimation with an adaptive bandwidth can better adapt to random component uncertainty,and M-CFC can improve the static security of the system.
文摘背景与目的肺癌术后3个月的生活质量在不同手术入路之间的关系尚不明确,本研究旨在对比单孔与多孔胸腔镜肺叶切除术后3个月患者的生活质量。方法收集2021年4月至2021年10月在四川省肿瘤医院胸外科行肺部手术患者的资料,采用欧洲癌症研究与治疗组织生活质量核心量表C30 (European Organization for Research and Treatment of Cancer quality of life core 30,EORTC QLQ-C30)和肺癌生活质量量表29 (Quality of Life QuestionnaireLung Cancer 29,QLQ-LC29)收集患者的生活质量资料。将基线资料中潜在混杂因素纳入多因素回归模型中校正,比较两组患者术后3个月的生活质量与传统临床结局。结果共纳入130例肺癌患者,男性57例(43.8%),女性73例(56.2%),平均年龄(57.1±9.5)岁。两组患者基线资料中,放置引流管数量具有统计学差异(P<0.001)。经回归模型校正后,在术后3个月时,两组患者全部症状及功能状态评分无明显差异(P均>0.05)。多孔组的手术时间(120.0 min vs 85.0 min,P=0.001)、术后住院时间(6.0 d vs 4.0 d,P=0.020)比单孔组更长,早期>2级并发症发生率(39.0%vs 10.1%,P=0.011)比单孔组更高。结论单孔与多孔胸腔镜肺叶切除术患者在术后3个月时具有相似的生活质量。单孔组在手术时间、术后住院时间及术后早期并发症等传统临床结局指标上可能具有一定的优势。
文摘该文提出了一种多端口直流–直流自耦变压器的拓扑,该多端口直流自耦变压器用于互联多个直流电压等级不同的直流系统。提出了多端口直流自耦变压器的潮流直接分析法以及潮流分解分析法,推导了多端口直流自耦变压器中各换流器额定电压与额定功率设计方法,设计了多端口直流自耦变压器的控制策略。以一个三端口直流自耦变压器为测试算例,在PSCAD/EMTDC下仿真验证了多端口直流自耦变压器的技术可行性。以互联±250、±320 k V和±400 k V直流系统为例,假设±250 k V和±320 k V系统的额定输入/输出功率分别为500 MW和1 000 MW,采用常规的多端口直流–直流变换器技术所需要的换流器总容量为3 000 MW,而采用多端口直流自耦变压器技术所需要总的换流器仅为775 MW,所使用的换流器总容量仅为现有技术的26%,显著节省了成本,降低了运行损耗。
文摘研究了一种基于多端口DC/DC变换器(multi-port DC/DC converters,MPC)的混合储能系统(hybrid energy storage system,HESS),并将其应用于直流微电网。针对脉动负荷功率突变对直流母线电压及蓄电池组正常运行造成剧烈冲击的问题,提出了一种基于移动平均滤波算法的自适应能量控制策略(adaptive energy control strategy,AECS)。首先,通过移动平均滤波算法将脉动负荷功率进行滤波,由蓄电池组承担平缓的功率变化,而由超级电容器补偿瞬时的功率突变,从而优化蓄电池充放电过程,延长其使用寿命;其次,引入超级电容端电压自适应控制,将超级电容端电压稳定在参考值附近;并对蓄电池组端口采用能量流均衡控制,使各蓄电池组荷电状态(state of charge,SOC)趋于一致。通过仿真和实验,验证了所提出的能量控制策略的有效性。
